题目内容

计算.(能简算的要用简便方法计算.)
5
12
×
7
25
×
3
14
7
9
÷
1
2
÷
35
36
1
14
×(
7
8
+7)
3
5
×
8
9
÷
5
8
5
6
×
1
4
+
5
6
×
3
4
96×
4
5
-36÷
5
4
+
4
5
×40
4
9
÷[(
1
3
-
1
9
)×2]
3
4
+
7
9
+
1
4
-
4
9
2
7
×
5
9
÷
2
7
×
5
9
11
12
-
3
7
)-(
4
7
-
7
12
3
5
×0.25+
3
5
×
3
4
分析:(1)(2)(4)按照从左到右的顺序计算;
(3)(5)(11)运用乘法分配律简算;
(6)(9)先把除法变成乘法,再运用乘法分配律简算;
(7)先算小括号里面的减法,再算中括号里面的乘法,最后算括号外的除法;
(8)运用加法交换律和加法结合律简算;
(10)先去括号,再根据加法结合律简算和减法的性质简算.
解答:解:(1)
5
12
×
7
25
×
3
14

=
7
60
×
3
14

=
1
40


(2)
7
9
÷
1
2
÷
35
36

=
14
9
×
36
35

=
8
5


(3)
1
14
×(
7
8
+7),
=
1
14
×
7
8
+7×
1
14

=
1
16
+
1
2

=
9
16


(4)
3
5
×
8
9
÷
5
8

=
8
15
×
8
5

=
64
75


(5)
5
6
×
1
4
+
5
6
×
3
4

=
5
6
×(
1
4
+
3
4
),
=
5
6
×1,
=
5
6


(6)96×
4
5
-36÷
5
4
+
4
5
×40,
=96×
4
5
-36×
4
5
+
4
5
×40,
=(96-36+40)×
4
5

=100×
4
5

=80;

(7)
4
9
÷[(
1
3
-
1
9
)×2],
=
4
9
÷[
2
9
×2],
=
4
9
÷
4
9

=1;

(8)
3
4
+
7
9
+
1
4
-
4
9

=(
3
4
+
1
4
)+(
7
9
-
4
9
),
=1+
1
3

=1
1
3


(9)
2
7
×
5
9
÷
2
7
×
5
9

=
2
7
×
5
9
×
7
2
×
5
9

=(
2
7
×
7
2
)×(
5
9
×
5
9
),
=1×
25
81

=
25
81


(10)(
11
12
-
3
7
)-(
4
7
-
7
12
),
=
11
12
-
3
7
-
4
7
+
7
12

=(
11
12
+
7
12
)-(
3
7
+
4
7
),
=
3
2
-1,
=
1
2


(11)
3
5
×0.25+
3
5
×
3
4

=
3
5
×(0.25+
3
4
),
=
3
5
×1,
=
3
5
点评:本题考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.
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